Intentional injury (violence) is the leading cause of death among African-American youth. The provision of medical services in an inner-city Emergency Department (ED) provides a critical opportunity to identify and characterize future timing and pattern of service use among youth with drug use, who may be missed in school-based samples, and who may not yet be in the criminal justice system. Health disparities exist in rates of violent injury among inner-city youth, many of whom are African-American, and are mirrored in limited access to substance use treatment services and over representation in the criminal justice system. Currently, there is a paucity of data on the timing, pattern, barriers, and trajectory of youth with multiple risks (illicit drug use and ED visit for acute violent injury) in terms of their intersection with health services (substance use treatment, mental health, medical) and criminal justice system, which limits the development of optimal timing and setting for interventions. Youth treated in the ED may have exacerbated rates of illicit drug use, and other risk behaviors (e.g., delinquency, HIV risk behaviors, weapon carriage) and different trajectories of outcomes and interactions with service use sectors based on presentation for intentional injury as compared to other complaints (medical, unintentional injuries). Understanding the outcomes and service utilization among inner- city youth with drug use with and without acute violent injury is critically important in developing prevention and treatment services to address these multiple risk factors. We propose a prospective observational study over a two-year period to identify a high risk group of youth with past year illicit drug use (N=800) seeking care in an inner city ED. The specific aims of the study, chosen to obtain data necessary to determine the location and content of subsequent interventions, are: (1) To describe characteristics of youth (ages 14-24; n=800) who report illicit drug use presenting to an urban ED for an acute violent injury (n=400), compared to youth with drug use who seek non-violence related ED care (n=400), including socio-demographic characteristics, problem severity (e.g., substance use, violence, HIV risk behaviors, etc.), enabling factors, and service utilization (i.e., substance use treatment, mental health, and medical); (2) To identify the trajectories of participants' interactions with health services during the two years following their ED visit and the key characteristics (i.e., predisposing, enabling, and need factors) associated with types of service use (substance use treatment, mental health, medical/ ED, and HIV testing) and barriers to these services; and, (3) To measure two-year outcomes for this cohort including, HIV risk behaviors, and to identify key socio- demographic and clinical characteristics of youth with drug use, who have poor outcomes in the two years after ED visit for intentional injury and other medical care. The proposed study represents collaboration with an established team of investigators who have a successful history of conducting substance use research in ED settings. There is a critical need to understand who is at greatest risk for poor outcomes (substance use, criminal justice, medical), and, who is least likely to enter treatment in order to target substance use and mental health interventions for those with greatest need. Results from this proposed study are essential to inform future ED prevention and intervention development to reduce health disparities among inner-city youth with substance use.